Fulltext-micro-irrigation-neseuzen.doc

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The Role of Micro Irrigation for Modern Agriculture Neşe Üzen*, Öner Çetin, Murat Karaer *

Dicle University, Agricultural Faculty, Department of Farm Structures and Irrigation Diyarbakır, Turkey, [email protected]

Abstract: In arid and semi-arid regions, irrigation improves economic returns and can boost production by up to 400%. On the other hand, the major problems on conventional (surface irrigation) irrigation for arid and semi arid region are soil salinity, soil alkalinity, soil dispersion, soil infertility, rise of water table and pollution of the surface and underground resources due to over-irrigation practices and over-application of chemical agri-inputs. Thus, Turkey has been made considerable an effort to convert from conventional irrigation systems to modern irrigation systems for the last decade. The rate of pressurized irrigation systems in Turkey increased to 5% from 20% by the support of the government, recently. Ministry of Agriculture, Food and Livestock have compensated 50 % of the all investment cost for the pressurized irrigation systems since 2007. Considering the positively effects of micro irrigation on water saving, liters of consuming water per kilo of crop by surface irrigation for cotton, alfalfa, corn, winter wheat, and water melon in semi arid region of Turkey were 2801, 1200, 943, 846 and 83, respectively. Whereas, liters of consuming water per kilo of crop by drip irrigation for cotton, corn and water melon are 1515, 474 and 68, respectively. Thus, the amount of irrigation water of 5 000-6 000 m 3 per ha are used in the modern irrigation systems (micro irrigation) while water more than 10 000 m 3 per ha are used for conventional irrigation. This paper presents impacts of micro-irrigation technologies in terms of crop water consumptive use, crop yield, environment, effective fertilizer use, sustainability and incomes for modern agriculture in Turkey and around the World. Keywords: Environment, micro irrigation, sustainability, water saving

1. Introduction Use of water in agriculture is very important for agricultural production and to decrease risk of drought. Global water use in agriculture is approximately 70% in not only Turkey but also in the world. The irrigation sector is under pressure to increase its efficiency since it is the major user of fresh water globally. This is exacerbated as water resources become scarcer due to climate change, increasing population and inappropriate irrigation applications, and as the competition for water from other economic and environmental uses. In the future, improved efficiency in the use of water for food production will become even more important. The amounts water used for industries and municipalities will increase while it for the agriculture decreases in future (Fig. 1).

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Figure 1. Estimated global water withdrawals (Mohtadollah and Bhatia., 1994.) In order to increase the contribution of irrigation on food production, FAO says, what is needed is improved efficiency in the use of irrigation water (FAO, 2003). A major advantage of water-saving technologies, particularly drip irrigation, is that as well as saving water they can increase yields and reduce the rate of salinization. Furthermore, since neither system brings water into contact with foliage, they can be used with brackish water for crops that are not too sensitive too salinity (Cetin, 2004.). Considering irrigation efficiency and environmental issues micro-irrigation, which is the precise application of water on or below the soil surface at low pressure using small devices that spray, mist, sprinkler or drip water, is becoming more attractive (Hla and Scherer, 2003). In recent decades, increased sales and improvements in technology have resulted in greater adoption of micro-irrigation worldwide. Drip irrigation is a common form of micro-irrigation. The statistics about irrigation shows the rapid growth in acreage under drip irrigation within many countries (Maadramootoo and Morrison, 2013). Several government and non-government organizations are actively promoting micro-irrigation in developing countries (Varma et al., 2006). Since the agriculture is an important sector of Turkey’s economy, the Government pays much attention to irrigation infrastructure investment and irrigation management within the framework of integrated water management concept (Gündoğdu, 2013). Thus, use of pressurized irrigation systems has recently increased in Turkey. Ministry of Food, Agriculture and Livestock have compensated 50 % of the all investment cost for the pressurized irrigation systems since 2007 (Cetin et al., 2010). In this article, the effects of micro irrigation on modern agriculture, soil and water resources sustainability are discussed. 2. Use of Micro-Irrigation for Agriculture

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2.1. Effect of Micro-Irrigation on Crop Yield and Water Saving Irrigation water requirements in micro-irrigation can be smaller when compared to the other irrigation methods. This is due to reduced wetted area; less water is lost to evaporation. These systems are also almost no surface runoff. Micro irrigation provides a constant supply of water in the crop zone and has been proven to provide a higher crop yield and increased water use efficiency over conventional irrigation methods. Postel (2000) claims that drip irrigation has the potential to at last double crop yield per unit water in many applications, including irrigation of most vegetables, cotton, sugar cane and orchard and vineyard crops. A collection of research results from various Indian research institutes indicates typical water use reductions with drip irrigation of 30-60% and typical yield increases of 2050% for a variety crops, including cotton, sugarcane, grapes, tomatoes, and bananas (Kooij et al., 2013). Gleick (2002) reported that “Shifting from conventional surface irrigation to drip irrigation in India has increased overall water productivity by 42-255% for crops as diverse as banana, cotton, sugar cane and sweet potato”. Due to its high water use efficiency, micro-irrigation is increasingly being used as a strategy to address water scarcity and poverty. Researchers, such as Shah (2011), have pointed to the water savings and yield increases due to micro-irrigation (Table 1). In addition to farm productivity (crop yield and output), farmer income and food security are also increased. With earlier harvests, labour costs are reduced. Improvements in drip irrigated crop quality have also been observed (Maadramootoo and Rigby, 1991). Table 1. Drip and surface irrigation- water saving and increase in yield (Shah, 2011) Yield (kg ha-1) Irrigation Crop Surface Drip Increase (%) Surface Drip Saving (%) Beet root 570 880 54 86 18 79 Bitter gourd 3 200 4 300 34 76 33 57 Broccoli 14 000 19 500 39 70 60 14 Chili 17 100 27 400 60 27 18 33 Cucumber 4 230 6 090 44 109 42 62 Okra 15 500 22 500 45 54 24 56 Onion 28 400 34 200 20 52 26 50 Potato 17 200 29 100 69 60 28 54 Sweet potato 4 240 5 890 39 63 25 60 Tomato 6 180 8 870 44 50 11 79 Banana 57 500 87 500 52 176 97 45 Grapes 26 400 32 500 23 53 28 47 Pomegranate 3 400 6 700 97 21 16 24 Watermelon 8 210 50 400 514 72 25 65 In Turkey, Tekinel et al., (1989) conducted the experiments on the effects of drip and conventional irrigation methods on the yields of tomato, strawberry, banana and citrus. The results showed that highest yields and crop quality were achieved by the drip irrigation. Also Cetin (1996) conducted an experiment using a surface (furrow) method of irrigation on second-crop maize in Harran Plain of Turkey, and obtained the highest

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yield of 10 150 kg/ha, and determined irrigation water requirement of maize as 1303 mm. Değirmenci et al. (1998) carried out research in the same plain using furrow irrigation and they obtained an average grain yield of 9 260 kg/ha and 873 mm of irrigation water. Yazar et al. (2002) obtained the highest yield of 11 920 kg/ha and on second-crop corn using drip irrigation and applied 581 mm of irrigation water. If these values are compared to the findings, then drip irrigation could save by as much as 55% compared to surface irrigation while a grain yield of 15-23% would be possible higher (Cetin, 2004). The studies on cotton in Harran Plain of Turkey showed that water requirement could be 1148 mm (Karaata, 1985), 1113 mm (Kanber et al.1991) and 937 mm (Cetin and Bilgel, 2002) by furrow irrigation. Whereas, Cetin and Bilgel (2002) showed that water requirement of cotton could be 619 mm by drip irrigation in order to approximately same yield. Accordingly drip irrigation resulted in not only higher cotton yield but also considerable water savings. The experiment results carried out by Cetin et al. (2002) showed that the average fruit yield of fresh market tomatoes irrigated by drip was 132,2 tones/ha while the yield was 54,8 tones/ha under conventional irrigation and local conditions of Eskişehir. 2.2. Environmentally Effects of Micro-Irrigation on Soil and Water Resources Another one of the significant advantage of the micro-irrigation systems are that water with relatively high salt content can be used by the system. Also treated and untreated wastewater can be applied in a manner which targets only suitable crops. Micro-irrigation is more appropriate than other irrigation methods for the reuse of wastewater because there is no aerosol generation and no wastewater comes into contact with plant foliage. There are also fewer problems with odours, ponding and runoff. In addition, studies suggest that the nitrogen present in wastewater is better absorbed by plants and less likely to pollute ground water when applied directly to plant roots. When using wastewater with micro-irrigation it is necessary to ensure that emitters do not clog. System must be closely monitored to ensure a uniform application and full functionality (Casey et al., 1999). On the other hand, much more less salt is added into the soil by micro irrigation compared with conventional irrigation. The water requirement of cotton for furrow and drip irrigation is approximately 1000 mm and 600 mm in Harran Plain of Turkey considering research results given by Cetin and Bilgel (2002), respectively. If 4 dS/m salt value becomes in the soil, salinity threshold value, amount in soil is 0.2%. Salt amount in soil for 0.90 m of the effective root depth is 24.3 t/ha, i.e., salinity threshold value (10000 m2 x 0.90 m x 1.35 t/m3 x 0,002 =24.3 t/ha). According to this calculation 2.56 t/ha/year and 1.536 t/ha/year salt added into the soil by furrow and drip irrigation, respectively. Consequently, the amount of the salt accumulated by drip irrigation in soil was much less than that of furrow due to less water use (Cetin, 2004). Through, good management of the micro irrigation systems the root zone moisture content can be maintained near field capacity throughout the season providing

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a level of water and air balance close to ideal for plant growth. During the dry season in humid areas, or in arid climates, micro-irrigation can have a significant effect on soil salinization. Also drainage problems do not occur. Besides these direct, private benefits to adopters, enumerated several other indirect, social benefits of drip irrigation: it reduces soil erosion and non-point pollution because water percolates only to low depth of soil; so fertilizers and pesticide residues do not mix with the water table; it promotes more efficient use of nutrients; it ensures better and longer moisture retention in the root zone. 2.3. Application of Fertilizers by Micro-Irrigation Drip irrigation is probably one of the most effective methods of water application. It generates a restricted root system requiring frequent nutrient supply. This may be satisfied by applying fertilizers with irrigation water by fertigation. A major innovation has been the development of fertilizer injectors which can be attached to micro-irrigation systems to allow for fertigation, thereby improving crop nutrient management. Micro-irrigation systems allow for a high level of control of chemical applications. Both water and fertilizer can be applied throughout the growing season in judicious amounts to match crop requirements. Additionally, other chemicals, such as herbicides, insecticides, fungicides, nematicides and growth regulators can be efficiently applied through micro irrigation systems to improve crop production. Additionally, incidence of pest and weed invasion, and other plant diseases, occurs less frequently due to a reduced wetted area and drier soil surface. By reducing the labour needed to protect crops, and by reducing pesticide/herbicide use, there is an overall financial saving to the farmers (Varma et al., 2006). Teixeira et al. (2011) remarked that fertigation promoted an increase of 36 % in nutrient use efficiency compared to conventional fertilization, for either nitrogen or potassium in banana crops. In addition, the study carried out by Darwish et al. (2002) showed that fertigation by drip enabled higher nutrient efficiency compared to traditional fertilizing (Table 2).

Table 2. Agronomic water and nutrient use efficiency of spring potato (Darwish et al., 2002) Nutrients use efficiency Water use efficiency DM g/g nutrient Treatment DM kg/m3 N P K Traditional 0.90 24.4 24.1 24.1 Fertigation 1.37 56.8 68.2 17.1 3. Probable Limitations in Micro-Irrigation

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Although technological development and simplification have reduced the overall cost of micro-irrigation systems, the technology is still expensive for farmer. Additionally, a high level of technical skill is required for proper system design, maintenance and optimal efficiency. Advancements to further reduce costs, labour and to facilitate the initial system design and installation will make this technology increasingly attractive to farmers. Due to the high initial investment required for taking up or switching to microirrigation systems, small farmers in developing countries have been slow to adopt this practice. In addition, a lack of cash and expertise, and the crop specificity associated with available micro-irrigation technologies, further reduce its desirability (Varma et al., 2006). There is potential to capitalize on the use of nanotechnology and biotechnology in micro-irrigation, particularly with respect to water quality improvement, filtration techniques, and reduced emitter clogging. The small openings can be easily clogged by soil particles, organic matter, algae, bacterial slime and chemical precipitates. For that reason, these systems require very good filtration. Nanomaterial-based biosensors can recognize, measure and monitor the presence of contaminants, with the potential to operate on site, in real time. Nanotechnology is used in soil moisture sensor design, achieving a high level of accuracy, rapid response rates, compact sizes and robustness. With these innovations, the challenge lies in transferring research into practice (OECD, 2011). Micro-irrigation systems can use saline and low quality water. However, a problem may occur from salt accumulating at the edges of the wetted zone during prolonged dry periods. Light rain can wash these salts into the root zone and cause injury to the plants. In arid climates, where the rainfall is less than 250 mm per year, an additional irrigation system (sprinkler or surface) may be necessary to leach accumulates salts from the soil between growing season (Cetin, 2004). 4. Conclusions Micro-irrigation has been particularly successful for horticultural, ornamental and landscape applications and has been applied to a wide range of climatic conditions from humid to arid and semi-arid regions and all topographic conditions. Its advantages with respect to water and energy savings, increased yields, improved fertilizer application, reduced the rate of salinization, eliminated wood and diseases, and reduced labour, are well recognized.Advances in emitter and dripper technology, the introduction of inexpensive drip tape, and the development of low-cost sand and screen filters have helped to expand acreage under micro-irrigation. A significant challenge is to apply drip irrigation technology to the production of cereal crops, particularly in developing countries. In these parts of the world, there are several social, technical and institutional challenges which must be overcome. Education and knowledge transfer must be accelerated. As a result, using the micro-irrigation systems will be vital important in terms of conservation or sustainability management of soil and water resources.

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